Toss sweet potatoes in 2-3T oil and roast at 350F until soft. Blend until very smooth with the broth and coconut milk in a high speed blender or food processor.
Heat 2T oil in a large pan and add the cumin and coriander seeds, toasting until just fragrant. Don't burn them!
Add the onion, turmeric, and garam masala and sautée for a few mins until translucent, then add the ginger and garlic, cooking for another 3-4 mins. This is where you’ll add the chili pepper if you like things extra hot.
Add the chickpeas and sautée for 2-3 mins, then pour the sweet potato mixture into the pan. Add the tomato paste, spinach and cilantro.
Cook until heated through.